I'm using pots for the first time to grow anything. I have watermelon and zucchini growing in my pots and was told the potting soil plus organic matter I added won't be enough nutrients for potted plants.

Which fertilizer should I be using? I suspect nitrogen isn't as important as it would be early in growing since the potting soil will likely offer enough nutrients in the early growing stage, is that right?

also......do I need to water more often plants in pots than I do with plants in a raised bed?

thank you.